Blaze: Fix the layout of loading state and error state of objective picker view

[itsmeichigo]

Closes: #13942

Description

This PR adds a quick fix for the Blaze campaign objective picker by pushing the footer view to the bottom in the loading and error states.

Steps to reproduce

• If you tested campaign objective before, log out of the app to clear the cached data.
• Log in to a store eligible for Blaze.
• Disconnect the internet connection.
• Start the Blaze campaign creation flow and select the objective list.
• Confirm that in the loading state, the footer is at the bottom of the screen.
• When the request time out, confirm that in the error state, the footer is at the bottom of the screen.

Testing information

Screenshots

Before	After

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• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

Reviewer (or Author, in the case of optional code reviews):

Please make sure these conditions are met before approving the PR, or request changes if the PR needs improvement:

• The PR is small and has a clear, single focus, or a valid explanation is provided in the description. If needed, please request to split it into smaller PRs.
• Ensure Adequate Unit Test Coverage: The changes are reasonably covered by unit tests or an explanation is provided in the PR description.
• Manual Testing: The author listed all the tests they ran, including smoke tests when needed (e.g., for refactorings). The reviewer confirmed that the PR works as expected on all devices (phone/tablet) and no regressions are added.

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 20.4. This milestone is due in less than 2 days. Please make sure to get it merged by then or assign it to a milestone with a later deadline.

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[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce iOS by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce iOS
	Build Number	pr13943-00e1db3
	Version	20.3
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	00e1db3
	App Center Build	WooCommerce - Prototype Builds #10838

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[hafizrahman]

I tested this on a 13 inch iPad simulator and the positioning looks correct now in both cases.